This paper uses the EEG analysis to investigate the relationship between pre-learning stress, frontal lope and long-term memory in the brain. The stress on learning stage is a challenge, especially in academic life. Stress also on learning stage affects the retrieval or recall from the memory. Nowadays; there are many recent works have discovered the relationship between stress, learning and memory performance based on different techniques. Some of these techniques are biological methods. Moreover, these methods have discovered the effect of stress based on hormones levels such as cortisol, or based on physiological effects such as blood pressure. However, these techniques have given conflicting discoveries because of the instability of hormones and an extensive number of related elements. The main aim of this research is to discover the relationship between Pre-learning stress, frontal lope, and long-term memory retrieval using EEG signals. The experimental results indicate that there is a relationship between theta rhythm in the frontal lobe and long-term memory retrieval during Pre-learning stress.

1. Bulletin of Electrical Engineering and Informatics
Vol. 9, No. 1, February 2020,pp. 141~145
ISSN: 2302-9285,DOI: 10.11591/eei.v9i1.1335  141
Journal homepage: http://beei.org
Frontal lobe and long-term memory retrieval analysis during
pre-learning stress using EEG signals
Omar Al Shorman1, Ahmad Al Shorman2
1
Electrical Engineering Department, Najran University, Najran, Saudi Arabia
2
Mechanical Engineering Department, Jordan University of Science and Technology, Irbid, Jordan
Article Info ABSTRACT
Article history:
Received Sep 23, 2018
Revised Jan 7, 2019
Accepted Sep 26, 2019
This paper uses the EEG analysis to investigate the relationship between
pre-learning stress, frontal lobe and long-term memory in the brain.
The stress on learning stage is a challenge, especially in academic life.
Stress also on learning stage affects the retrieval or recall from the memory.
Nowadays; there are many recent works have discovered the relationship
between stress, learning and memory performance based on different
techniques. Some of these techniques are biological methods.
Moreover, these methods have discovered the effect of stress based on
hormones levels such as cortisol, or based on physiological effects such as
blood pressure. However, these techniques have given conflicting discoveries
because of the instability of hormones and an extensive number of related
elements. The main aim of this research is to discover the relationship
between Pre-learning stress, frontal lobe, and long-term memory retrieval
using EEG signals. The experimental results indicate that there
is a relationship between theta rhythm in the frontal lobe and long-term
memory retrieval during Pre-learning stress.
Keywords:
EEG
Frontal lobe
Long-term memory
Pre-Learning stress
This is an open access article under the CC BY-SA license.
Corresponding Author:
Omar Al Shorman,
Electrical Engineering Department,
Najran University, Najran,SaudiArabia.
Email: omar2007_ahu@yahoo.com
1. INTRODUCTION
These days, there are many people in the world suffer from worry and stress through regular daily
existence. In 2008, the American Institute of Stress reported that approximately 80% of college students
normally feel stress often in their daily learning tasks and assignments. Moreover, in 2013, American College
Health Association also showed that approximately 30.7% of undergraduate college students suffer from
stress during their academic life. Importantly, these discoveries demonstrate very dangerous risk of stress.
Hazardously, chronic stress capable to hurt a hippocampus region in the brain [1, 2]. However, the effect of
stress for the human body could be physical (i.e. increasing of heart rate), emotional (i.e. anger, anxiety,
and depression), behavioral (i.e. lacking of eating and sleeping), and cognitive (i.e. learning and memory
problems) [3-5]. Consequently, stress influences the human daily activities such as managing life's tasks,
working and educational performance depending on the kind of stressors) [6]. Moreover, when the human
faces stress biochemical reactions will be secreted as a response of stressor, which includes increasing
of several body hormones’levels such as cortisol.
Stress can also influence short-term memory (STM) and long–term memory (LTM) and for all
memory stages: encoding, retention (consolidation), a nd retrieval (recall) [7-11]. Furthermore, there are many
factors interferes with studying the affection of stress on learning and memory processes which increase

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Bulletin of Electr Eng & Inf, Vol. 9, No. 1, February 2020 : 141 – 145
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the complexity of discovering that affection. On the other hand, the effect of stress on memory
(encoding, retention and retrieval) may be varied during the learning or during the time of stressor.
Studying the effect of stress on learning and memory processes from psychobiological point of view
have focused on different factors related with stress [12], which includes, nature of stressor and timing of
stressor [13], intensity and severity of stressor [14], source of stressor, gender [15],
individual differences [16] and learning types [17]. To diagnose the mental disorders and abnormalities for
humans; recently, the electroencephalogram (EEG) has become very valuable and vital technique.
The main goal of this technique is to measure brain activities. Morover, the desired features could be
extracted from the signals, which are recorded from the scalp of the brain.
Nowadays, EEG has been used extensively to detect and study human stress [18]. In EEG analysis,
alpha, theta and gamma rhythms have an essential role in hum an cognitive process and functionality of
the brain. Moreover, Theta rhythm is associated and related to memory and learning process, especially for
encoding and retrieval phases in all types of memories [19]. In [20], memory retrieval process has been
discussed, however, the authors discovered that power of parrietal theta increases for normal memory
retrieval. Moreover, In [21], the main power for theta and gamma bands are measured during memory
encoding stage. In conclusion, successful encoding is related to decreasing alpha band activity at both
pre-frontaland occipital lobes.
Stress assessment based on EEG analysis is discussed in [22], in one hand, busy brain decreases
alpha power and increases beta power. In the other hand, the power in left pre-frontal increases during
stress [23, 24]. Until now, studying pre-learning stress using EEG signals still infant and there is a lack of
contributes in this regard [25-27]. Twenty-two non-smoking, undergraduate university male healthy students
between 18 and 22 of age participated in the experiment. According to exclusion criteria; all subjects must be
healthy and none of them has an illness history, acute disorders, chronic disorders, or took medication or
drugs. All subjects will sign written informed consent. The experiment conducted afternoon (as known
medically the cortisol level is stable in afternoon time). Moreover, cortisol level is high in the morning and
low at the night. The experiment consists of two sessions. The participants in the experiment are divided into
2 groups, first group is called control group and second group is called pre-stressed group.
In more details, for the control group; all subjects in this group are learned some neutral content or
list of neutral words without facing the stress and in comfortable state. In the pre-stressed group,
before the encoding phase in 5 minutes, the subjects were laid under stressor, after that, they are learned
some neutral content or list of neutral words. After 2 months (to measure the long term memory retrieval)
with comfortable state,the subjectsin both groups asked verbally to free recall the neutral contents that were
learned previously in the encoding phase for 5 minutes. Importantly, 128 channels EEG were used in both
groups to record the EEG activities. The main contribution of this paper is to discover the relationship
between theta rhythm and frontallobe during pre-learning stress.
2. RESEARCH METHOD
All the latest studies in the effect of stress on memory and learning have investigated
the relationships between biological factors (i.e. Hormones) and memory performance. According to these
studies, it is observable that there is a conflict in the findings. This research conflict comes from
the instability of human hormones. Moreover, there are many factors such as, gender, age, mood, health
status, drugs usage, smoking and so forth interferes with studying stress. Importantly, all these factors play
a crucial role of inconsistency in the findings and the result. So, the searching for another technique to study
stress is becoming very important and useful. However, stress affects learning stage and all memory stages
(learning, consolidation and recall) in the brain that depends mainly on the time of the stressor.
Moreover, stress may interfere with encoding stage, consolidation stage and retrieval stage as
shown in Figure 1.
Retrieval phase of long-term memory is very important. Remembering the informa tion that
previously encoded and stored in the memory is very important for the humans. Importantly, enhancement
the memory retrieval leads to enhancement human performance and daily activities especially, academic
performance for students. Moreover, strong and deep learning (encoding) leads to strong recall (retrieval).
That why the motivation of this research comes from. In this research study, EEG analysis is applied to
discover the effect of pre-learning stress in EEG bands (alpha, beta, theta and gamma) in the frontal lobe.
The methodology of the study is shown in Figure 2.

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Frontal lobe and long-term memory retrieval analysis during pre-learning stress… (Omar Al Shorman)
143
Figure 1. The relationship between stress and time of stressor for learning and memory stages
Figure 2. Flow chart for EEG pre-stress analysis algorithm
3. RESULTS AND ANALYSIS
In order to assess the effect of pre-learning stress; the EEG data [24] has been recorded from
the subjects using 128 EEG channels system. The recording process was conducted after two months from
the learning session to assess long-term memory. Firstly, notch filter has been used to filter the signal and to
remove AC power noise. After that, the filtered signal is passed through band pass filter with cut-off
frequency 0.1-30 HZ. As the EEG data is sensitive to other artifacts such as EOG and EMG, Independent
component analysis (ICA) is applied to remove these artifacts. EEG Lab MATLAB toolbox for EEG
processing is used to process the EEG data. Mean power spectrum for EEG bands theta (4-8 Hz) for 128
channels were recorded and extracted. Consequently, the changes in EEG rhythm (theta) in frontal lobe were
shown. In addition to the changes in the rhythms, paired sample t-test is used to investigate the significance
of the difference in theta band during long-term memory retrieval and eyes open (EO, control) in frontallobe,
as shown in Figures 3, 4 and 5. Figure 3 shows the main power for theta band, beta band and alpha band at
frontallobe during long-term memory retrieval.

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Figure 3. Mean power of Theta,beta and alpha bands at Frontallobe during LTM retrieval
Figure 4 shows the main power for theta band,beta band and alpha band at frontallobe during Eyes
Open (EO) state. The difference of theta band power between Eyes Open (EO) state and long-term memory
retrieval at frontallobe is shown in Figure 5.
Figure 4. Mean power of Theta,beta and alpha bands
at frontallobe during EO
Figure 5. Difference of theta band power between
EO and LTM retrieval at frontallobe
4. CONCLUSION
In conclusion, the current study shows effects of pre-learning stress in theta rhythm at the frontal
lobe in the brain. In general, it has been concluded that the theta band (4-8 Hz) means power increased at
frontal lobe during long term memory retrieval for the pre-stressed group compared with theta power in
frontal lobe for the control group. The results suggest that pre-learning stress increases theta main power in
the frontal lobe. That also may consider as a long-term memory retrieval performance index.
Furthermore, statistically, paired sample t-test showed that the P value for theta band between long-term
memory LTM retrieval for pre-stressed group and EO at frontallobe was equaled to 0.0431.
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